/*
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */
package net.sf.l2j.gameserver.scripting;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.InvalidClassException;
import java.io.LineNumberReader;
import java.io.ObjectInputStream;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.script.Compilable;
import javax.script.CompiledScript;
import javax.script.ScriptContext;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import javax.script.SimpleScriptContext;

import javolution.util.FastMap;
import net.sf.l2j.Config;

//import com.l2jserver.script.jython.JythonScriptEngine;
/**
 * Caches script engines and provides funcionality for executing and managing
 * scripts.<BR>
 * 
 * @author KenM
 */
public final class L2ScriptEngineManager {
	private static final Logger _log = Logger
			.getLogger(L2ScriptEngineManager.class.getName());
	public final static File SCRIPT_FOLDER = new File(
			Config.DATAPACK_ROOT.getAbsolutePath(), "data/scripts");

	public static L2ScriptEngineManager getInstance() {
		return SingletonHolder._instance;
	}

	private final Map<String, ScriptEngine> _nameEngines = new FastMap<String, ScriptEngine>();
	private final Map<String, ScriptEngine> _extEngines = new FastMap<String, ScriptEngine>();
	private final List<ScriptManager<?>> _scriptManagers = new LinkedList<ScriptManager<?>>();
	private final CompiledScriptCache _cache;
	private File _currentLoadingScript;
	// Configs
	// TODO move to config file
	/**
	 * Informs(logs) the scripts being loaded.<BR>
	 * Apply only when executing script from files.<BR>
	 */
	private final boolean VERBOSE_LOADING = false;
	/**
	 * If the script engine supports compilation the script is compiled before
	 * execution.<BR>
	 */
	private final boolean ATTEMPT_COMPILATION = true;
	/**
	 * Use Compiled Scripts Cache.<BR>
	 * Only works if ATTEMPT_COMPILATION is true.<BR>
	 * DISABLED DUE ISSUES (if a superclass file changes subclasses are not
	 * recompiled where they should)
	 */
	private final boolean USE_COMPILED_CACHE = false;
	/**
	 * Clean an previous error log(if such exists) for the script being loaded
	 * before trying to load.<BR>
	 * Apply only when executing script from files.<BR>
	 */
	private final boolean PURGE_ERROR_LOG = true;

	private L2ScriptEngineManager() {
		ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
		List<ScriptEngineFactory> factories = scriptEngineManager
				.getEngineFactories();
		if (USE_COMPILED_CACHE)
			_cache = this.loadCompiledScriptCache();
		else
			_cache = null;
		_log.info("Initializing Script Engine Manager");
		for (ScriptEngineFactory factory : factories)
			try {
				ScriptEngine engine = factory.getScriptEngine();
				boolean reg = false;
				for (String name : factory.getNames()) {
					ScriptEngine existentEngine = _nameEngines.get(name);
					if (existentEngine != null) {
						double engineVer = Double.parseDouble(factory
								.getEngineVersion());
						double existentEngVer = Double
								.parseDouble(existentEngine.getFactory()
										.getEngineVersion());
						if (engineVer <= existentEngVer)
							continue;
					}
					reg = true;
					_nameEngines.put(name, engine);
				}
				if (reg)
					_log.info("Script Engine: " + factory.getEngineName() + " "
							+ factory.getEngineVersion() + " - Language: "
							+ factory.getLanguageName()
							+ " - Language Version: "
							+ factory.getLanguageVersion());
				for (String ext : factory.getExtensions())
					if (!ext.equals("java")
							|| factory.getLanguageName().equals("java"))
						_extEngines.put(ext, engine);
			} catch (Exception e) {
				_log.warning("Failed initializing factory. ");
				e.printStackTrace();
			}
		this.preConfigure();
	}

	private void preConfigure() {
		// java class path
		// Jython sys.path
		String dataPackDirForwardSlashes = SCRIPT_FOLDER.getPath().replaceAll(
				"\\\\", "/");
		String configScript = "import sys;sys.path.insert(0,'"
				+ dataPackDirForwardSlashes + "');";
		try {
			this.eval("jython", configScript);
		} catch (ScriptException e) {
			_log.severe("Failed preconfiguring jython: " + e.getMessage());
		}
	}

	private ScriptEngine getEngineByName(String name) {
		return _nameEngines.get(name);
	}

	private ScriptEngine getEngineByExtension(String ext) {
		return _extEngines.get(ext);
	}

	public void executeScriptList(File list) throws IOException {
		if (list.isFile()) {
			LineNumberReader lnr = new LineNumberReader(new InputStreamReader(
					new FileInputStream(list)));
			String line;
			File file;
			while ((line = lnr.readLine()) != null) {
				String[] parts = line.trim().split("#");
				if (parts.length > 0 && !parts[0].startsWith("#")
						&& parts[0].length() > 0) {
					line = parts[0];
					if (line.endsWith("/**"))
						line = line.substring(0, line.length() - 3);
					else if (line.endsWith("/*"))
						line = line.substring(0, line.length() - 2);
					file = new File(SCRIPT_FOLDER, line);
					if (file.isDirectory() && parts[0].endsWith("/**"))
						this.executeAllScriptsInDirectory(file, true, 32);
					else if (file.isDirectory() && parts[0].endsWith("/*"))
						this.executeAllScriptsInDirectory(file);
					else if (file.isFile())
						try {
							this.executeScript(file);
						} catch (ScriptException e) {
							this.reportScriptFileError(file, e);
						}
					else
						_log.warning("Failed loading: ("
								+ file.getCanonicalPath() + ") @ "
								+ list.getName() + ":" + lnr.getLineNumber()
								+ " - Reason: doesnt exists or is not a file.");
				}
			}
			lnr.close();
		} else
			throw new IllegalArgumentException(
					"Argument must be an file containing a list of scripts to be loaded");
	}

	public void executeAllScriptsInDirectory(File dir) {
		this.executeAllScriptsInDirectory(dir, false, 0);
	}

	public void executeAllScriptsInDirectory(File dir, boolean recurseDown,
			int maxDepth) {
		this.executeAllScriptsInDirectory(dir, recurseDown, maxDepth, 0);
	}

	private void executeAllScriptsInDirectory(File dir, boolean recurseDown,
			int maxDepth, int currentDepth) {
		if (dir.isDirectory()) {
			for (File file : dir.listFiles())
				if (file.isDirectory() && recurseDown
						&& maxDepth > currentDepth) {
					if (VERBOSE_LOADING)
						_log.info("Entering folder: " + file.getName());
					this.executeAllScriptsInDirectory(file, recurseDown,
							maxDepth, currentDepth + 1);
				} else if (file.isFile())
					try {
						String name = file.getName();
						int lastIndex = name.lastIndexOf('.');
						String extension;
						if (lastIndex != -1) {
							extension = name.substring(lastIndex + 1);
							ScriptEngine engine = this
									.getEngineByExtension(extension);
							if (engine != null)
								this.executeScript(engine, file);
						}
					} catch (FileNotFoundException e) {
						// should never happen
						e.printStackTrace();
					} catch (ScriptException e) {
						this.reportScriptFileError(file, e);
						// e.printStackTrace();
					}
		} else
			throw new IllegalArgumentException(
					"The argument directory either doesnt exists or is not an directory.");
	}

	public CompiledScriptCache getCompiledScriptCache() throws IOException {
		return _cache;
	}

	public CompiledScriptCache loadCompiledScriptCache() {
		if (USE_COMPILED_CACHE) {
			File file = new File(SCRIPT_FOLDER, "CompiledScripts.cache");
			if (file.isFile()) {
				ObjectInputStream ois = null;
				try {
					ois = new ObjectInputStream(new FileInputStream(file));
					CompiledScriptCache cache = (CompiledScriptCache) ois
							.readObject();
					return cache;
				} catch (InvalidClassException e) {
					_log.log(
							Level.SEVERE,
							"Failed loading Compiled Scripts Cache, invalid class (Possibly outdated).",
							e);
				} catch (IOException e) {
					_log.log(Level.SEVERE,
							"Failed loading Compiled Scripts Cache from file.",
							e);
				} catch (ClassNotFoundException e) {
					_log.log(
							Level.SEVERE,
							"Failed loading Compiled Scripts Cache, class not found.",
							e);
				} finally {
					try {
						ois.close();
					} catch (Exception e) {
					}
				}
				return new CompiledScriptCache();
			} else
				return new CompiledScriptCache();
		}
		return null;
	}

	public void executeScript(File file) throws ScriptException,
			FileNotFoundException {
		String name = file.getName();
		int lastIndex = name.lastIndexOf('.');
		String extension;
		if (lastIndex != -1)
			extension = name.substring(lastIndex + 1);
		else
			throw new ScriptException(
					"Script file ("
							+ name
							+ ") doesnt has an extension that identifies the ScriptEngine to be used.");
		ScriptEngine engine = this.getEngineByExtension(extension);
		if (engine == null)
			throw new ScriptException("No engine registered for extension ("
					+ extension + ")");
		else
			this.executeScript(engine, file);
	}

	public void executeScript(String engineName, File file)
			throws FileNotFoundException, ScriptException {
		ScriptEngine engine = this.getEngineByName(engineName);
		if (engine == null)
			throw new ScriptException("No engine registered with name ("
					+ engineName + ")");
		else
			this.executeScript(engine, file);
	}

	public void executeScript(ScriptEngine engine, File file)
			throws FileNotFoundException, ScriptException {
		BufferedReader reader = new BufferedReader(new InputStreamReader(
				new FileInputStream(file)));
		if (VERBOSE_LOADING)
			_log.info("Loading Script: " + file.getAbsolutePath());
		if (PURGE_ERROR_LOG) {
			String name = file.getAbsolutePath() + ".error.log";
			File errorLog = new File(name);
			if (errorLog.isFile())
				errorLog.delete();
		}
		if (engine instanceof Compilable && ATTEMPT_COMPILATION) {
			ScriptContext context = new SimpleScriptContext();
			context.setAttribute("mainClass",
					getClassForFile(file).replace('/', '.').replace('\\', '.'),
					ScriptContext.ENGINE_SCOPE);
			context.setAttribute(ScriptEngine.FILENAME, file.getName(),
					ScriptContext.ENGINE_SCOPE);
			context.setAttribute("classpath", SCRIPT_FOLDER.getAbsolutePath(),
					ScriptContext.ENGINE_SCOPE);
			context.setAttribute("sourcepath", SCRIPT_FOLDER.getAbsolutePath(),
					ScriptContext.ENGINE_SCOPE);
			// context.setAttribute(JythonScriptEngine.JYTHON_ENGINE_INSTANCE,
			// engine, ScriptContext.ENGINE_SCOPE);
			this.setCurrentLoadingScript(file);
			ScriptContext ctx = engine.getContext();
			try {
				engine.setContext(context);
				if (USE_COMPILED_CACHE) {
					CompiledScript cs = _cache.loadCompiledScript(engine, file);
					cs.eval(context);
				} else {
					Compilable eng = (Compilable) engine;
					CompiledScript cs = eng.compile(reader);
					cs.eval(context);
				}
			} finally {
				engine.setContext(ctx);
				this.setCurrentLoadingScript(null);
				context.removeAttribute(ScriptEngine.FILENAME,
						ScriptContext.ENGINE_SCOPE);
				context.removeAttribute("mainClass", ScriptContext.ENGINE_SCOPE);
			}
		} else {
			ScriptContext context = new SimpleScriptContext();
			context.setAttribute("mainClass",
					getClassForFile(file).replace('/', '.').replace('\\', '.'),
					ScriptContext.ENGINE_SCOPE);
			context.setAttribute(ScriptEngine.FILENAME, file.getName(),
					ScriptContext.ENGINE_SCOPE);
			context.setAttribute("classpath", SCRIPT_FOLDER.getAbsolutePath(),
					ScriptContext.ENGINE_SCOPE);
			context.setAttribute("sourcepath", SCRIPT_FOLDER.getAbsolutePath(),
					ScriptContext.ENGINE_SCOPE);
			this.setCurrentLoadingScript(file);
			try {
				engine.eval(reader, context);
			} finally {
				this.setCurrentLoadingScript(null);
				engine.getContext().removeAttribute(ScriptEngine.FILENAME,
						ScriptContext.ENGINE_SCOPE);
				engine.getContext().removeAttribute("mainClass",
						ScriptContext.ENGINE_SCOPE);
			}
		}
	}

	public static String getClassForFile(File script) {
		String path = script.getAbsolutePath();
		String scpPath = SCRIPT_FOLDER.getAbsolutePath();
		if (path.startsWith(scpPath)) {
			int idx = path.lastIndexOf('.');
			return path.substring(scpPath.length() + 1, idx);
		}
		return null;
	}

	public ScriptContext getScriptContext(ScriptEngine engine) {
		return engine.getContext();
	}

	public ScriptContext getScriptContext(String engineName) {
		ScriptEngine engine = this.getEngineByName(engineName);
		if (engine == null)
			throw new IllegalStateException("No engine registered with name ("
					+ engineName + ")");
		else
			return this.getScriptContext(engine);
	}

	public Object eval(ScriptEngine engine, String script, ScriptContext context)
			throws ScriptException {
		if (engine instanceof Compilable && ATTEMPT_COMPILATION) {
			Compilable eng = (Compilable) engine;
			CompiledScript cs = eng.compile(script);
			return context != null ? cs.eval(context) : cs.eval();
		} else
			return context != null ? engine.eval(script, context) : engine
					.eval(script);
	}

	public Object eval(String engineName, String script) throws ScriptException {
		return this.eval(engineName, script, null);
	}

	public Object eval(String engineName, String script, ScriptContext context)
			throws ScriptException {
		ScriptEngine engine = this.getEngineByName(engineName);
		if (engine == null)
			throw new ScriptException("No engine registered with name ("
					+ engineName + ")");
		else
			return this.eval(engine, script, context);
	}

	public Object eval(ScriptEngine engine, String script)
			throws ScriptException {
		return this.eval(engine, script, null);
	}

	public void reportScriptFileError(File script, ScriptException e) {
		String dir = script.getParent();
		String name = script.getName() + ".error.log";
		if (dir != null) {
			File file = new File(dir + "/" + name);
			FileOutputStream fos = null;
			try {
				if (!file.exists())
					file.createNewFile();
				fos = new FileOutputStream(file);
				String errorHeader = "Error on: " + file.getCanonicalPath()
						+ "\r\nLine: " + e.getLineNumber() + " - Column: "
						+ e.getColumnNumber() + "\r\n\r\n";
				fos.write(errorHeader.getBytes());
				fos.write(e.getMessage().getBytes());
				_log.warning("Failed executing script: "
						+ script.getAbsolutePath() + ". See " + file.getName()
						+ " for details.");
			} catch (IOException ioe) {
				_log.warning("Failed executing script: "
						+ script.getAbsolutePath()
						+ "\r\n"
						+ e.getMessage()
						+ "Additionally failed when trying to write an error report on script directory. Reason: "
						+ ioe.getMessage());
				ioe.printStackTrace();
			} finally {
				try {
					fos.close();
				} catch (Exception e1) {
				}
			}
		} else
			_log.warning("Failed executing script: "
					+ script.getAbsolutePath()
					+ "\r\n"
					+ e.getMessage()
					+ "Additionally failed when trying to write an error report on script directory.");
	}

	public void registerScriptManager(ScriptManager<?> manager) {
		_scriptManagers.add(manager);
	}

	public void removeScriptManager(ScriptManager<?> manager) {
		_scriptManagers.remove(manager);
	}

	public List<ScriptManager<?>> getScriptManagers() {
		return _scriptManagers;
	}

	/**
	 * @param currentLoadingScript
	 *            The currentLoadingScript to set.
	 */
	protected void setCurrentLoadingScript(File currentLoadingScript) {
		_currentLoadingScript = currentLoadingScript;
	}

	/**
	 * @return Returns the currentLoadingScript.
	 */
	protected File getCurrentLoadingScript() {
		return _currentLoadingScript;
	}

	@SuppressWarnings("synthetic-access")
	private static class SingletonHolder {
		protected static final L2ScriptEngineManager _instance = new L2ScriptEngineManager();
	}
}
